An exemplary embodiment of the present invention relates to cables for transmitting electrical and optical signals, especially with coaxial cables.
In contrast to mobile radio stations used up until now, so-called Remote Radio Head (RRH) stations have the advantage that a lower transmission capacity is needed since the high-frequency transmitter is situated much closer to the antenna and consequently only a shorter high-frequency line to the antenna is needed. This fact increases the efficiency of the mobile radio station substantially. Moreover, the transmitter mast of an RRH station can be installed up to several hundred meters away from the base station.
The term remote radio head is used in mobile radio technology to refer to the outdoor and weather-proof installation of the power supply, the transmitter and receiver module, the output amplifier and the filters on the antennas. The communication with the base station is usually effectuated via a fiberglass connection.
Up until now, the structure of RRH mobile radio stations with remote high-frequency transmitters has been expensive in comparison to conventionally constructed mobile radio systems since a power supply line and a data line had to be installed. So far, this is only cost-effective in the case of fairly long cables. However, an RRH mobile radio system entails considerable cost advantages in comparison to a conventionally constructed mobile radio system during ongoing operation.
In the state of the art, cables are known in which several types of conductors are combined in order to lower installation costs or in cases where exceptional difficulties have to be overcome.
German Utility Model DE 20 2007010626 U1 discloses a data-energy hybrid line. This hybrid line is intended for applications in high-frequency shielded areas and it combines electrically shielded direct voltage lines with potential-free optical fibers in one cable. U.S. Pat. Appln. 2003/0121694 A1 discloses a cable in which a power line, a data line and a control line are combined into a single cable having a shared sheathing.
The cables known from the state of the art, however, are not suitable for facilitating the conversion of existing mobile radio stations to modern RRH technology.